Solar power generation system

ABSTRACT

A solar power generation system is provided for more efficiently and cost-effectively generating and delivering power. The solar power generation system includes a plurality of distributed power converter nodes each configured to convert DC power received from a solar module into a deadband DC waveform. The deadband DC power generated by each power converter node is then transmitted to a centralized grid interface box, which is configured to unfold the deadband DC waveform into an AC signal suitable for transmission to an electric power grid.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalPatent Application No. 62/540,951, filed Aug. 3, 2017, and U.S.Provisional Patent Application No. 62/567,488, filed Oct. 3, 2017; thecontents of both of which are hereby incorporated by reference in theirentirety.

BACKGROUND

Photovoltaic (PV) power is one of the world's fastest growing renewableenergy resources. In order to continue this growth trend, however,access to solar power must be improved in residential, commercial, andutility-scale sectors. In each of these power consumption sectors, thecost per watt of solar power generated is paramount. If the cost perwatt of a given solar power generation system is uncompetitive withtraditional power generation sources in the same sector, the solar powersystem becomes inaccessible and/or commercially unviable to the majorityof power consumers in that sector. As a result, growth of PV-based powersystems is dependent on the continued reduction of the cost per watt forpower generated by these systems.

The cost per watt associated with solar power generation systems is tiedto almost all elements of the system. As just some examples, costsassociated with the production and sale of solar power systemcomponents, the installation of those components, and the on-goingmaintenance of those components each impact the cost per watt of theoverall system. Likewise, the electrical efficiency of the system inharvesting and transmitting usable power significantly impacts thecost-per-watt of the system as a whole. Innovations relating to anyaspect of a solar power system that provide improvements to any or allof these cost centers can lead to reductions in system cost-per-watt.Indeed, numerous aspects of existing solar power systems—beyond solarpanels themselves—are ripe for improvement.

Solar panels are designed to use the photovoltaic effect to convertphotons emitted by the sun into direct current (DC) power. However, inorder to produce power useable for most existing environments, the DCpower output by the solar panels must be converted into alternatingcurrent (AC) power. The DC to AC conversion of solar generated power isconventionally accomplished by an inverter, which can implemented into apower generation system in a variety of ways.

For systems configured to interface with the electric grid, invertersare generally implemented into solar power generation systems with acentralized or module-level architecture. In a fully centralizedconfiguration, an example of which is shown in FIG. 1A, a singleinverter is positioned between strings of solar modules and the electricgrid. In this configuration, each string of solar modules delivers DCpower to the centralized inverter, which then converts the collectivelyinput DC power into AC power output. The AC power output is thentransmitted to the grid. As a result, centralized inverter systems aresometimes referred to as “string inverter” systems. A similarconfiguration is shown in FIG. 1B, which illustrates a semi-centralizedstring inverter configuration using multiple inverters (as opposed toone). In this configuration, each inverter is again positioned betweenstrings of solar modules and the electric grid. Each inverter convertsthe DC power received from its respective string of solar modules,converts that input power to AC, and delivers the AC power—along withthe other inverters—to the electric grid.

Centralized and semi-centralized string inverter systems are used in awide array of environments from solar farms to residential applications.By connecting inverters to strings of solar modules, the number ofinverters needed is reduced and the ease of installation for theinverters is improved. These systems, however, have a number ofdrawbacks and limitations.

Solar modules strings are limited at any given time by the leastproductive module in the string. In other words, a given solar modulestring will only produce as much power as the least productive module.In environments where certain solar modules might be shaded while othersare not (e.g., large strings or strings having modules facing differentdirections), this can significantly reduce the efficiency with which thesolar modules can harvest energy. Moreover, string inverterarchitectures are more susceptible to losses in power generation when asolar module is damaged or otherwise not functioning properly.

A further disadvantage of string inverter systems is their lack ofcontrol at the solar module level. For example, conventional stringinverters can only track maximum power (e.g., as part of an MPPTalgorithm) down to the string level as opposed to the panel level. Ifthere is a weak module in the string, the weakened module will limit theamount of power that can be extracted from the string of modules.Additionally, when solar modules are stacked, high voltage potentials(e.g., 600-2000V) can be reached and remain present even when theinverter is off. These high voltage potentials can present a fire hazardif any of the electrical connections in the solar array become loose ordamaged, which necessitates additional hardware close to the module tomitigate against this risk.

String inverters also have inherent inefficiencies resulting from highvoltage transistors that must be used to synthesize sine waves. Inparticular, the high voltage of the solar module string (e.g., 600-2000Vas noted above) requires high voltage MOSFETs or IGBTs in the stringinverter. The MOSFETs and IGBTs must switch at high frequencies, whichgenerates more heat losses that a comparably low voltage MOSFET. Thehigh voltage devices also require larger inductors and capacitors. As aresult, string inverter systems are limited with respect to theirefficiency in inverting power from solar modules.

FIGS. 1C and 1D illustrate examples of existing module-levelarchitectures. In particular, FIG. 1C shows a micro-inverter systemarchitecture in which inverters are provided for each solar module inthe system. These “micro” inverters are typically installed on the backof modules of solar panels, integrated as part of the modulesthemselves, or otherwise provided proximate to the modules. Eachmicro-inverter is configured to convert the DC power received from itsrespective solar panel into AC power, which is then transmitted from theinverter to the electric grid. Micro-inverter architectures are popularin residential environments where the total number of solar modules islower. As a result, the micro-inverter architecture may in somecircumstances be configured to deliver AC power harvested from variousinverters directly to a building load as indicted in FIG. 1C.

FIG. 1D illustrates another module-level architecture in which DCoptimizers are provided at each solar module. In this DC optimizerinverter system, each DC optimizer is configured to condition the DCpower received from its respective solar module and transmit thisconditioned DC power to a string inverter provided between theoptimizers and electric grid. Although the system makes use of a stringinverter, the DC optimizers are provided in the system at themodule-level analogously the aforementioned micro-inverters.

These module-level architectures are popular in residential applicationsand other environments where less modules are used. Because of themodule-level nature of these systems, they are better suited forenvironments susceptible to shading. In particular, both micro-inverterand DC optimizer systems allow for optimization module-by-module and, asa result, are typically more efficient than a string inverter systemusing the same number of modules. These module-level architectures alsohave a number of drawbacks and limitations.

As an example, both micro-inverter and DC optimizer systems are morecostly than comparable string inverter systems. In micro-invertersystems, each micro-inverter requires a full array of electronicsnecessary to convert DC power from solar modules into AC, includinglarge transformers and extra transistors. Moreover, an individualmicro-inverter is provided for each solar module, increasing not onlythe total cost of componentry but also significantly increasing the costand complexity of installation. In DC optimizer systems, the presence ofoptimizers themselves increases the cost of system components andinstallation cost. In addition, DC optimizer systems still require highvoltage MOSFETs or IGBTS along with large magnetics to convert DC to ACpower, thereby reducing efficiency of the overall system. Furthermore,DC electric transmission and distribution systems are highly susceptibleto arc faults, due to the nature of DC transmission. To protect againstpotential hazards from arc faults, including the risk of fire and therisk of electric shock, conventional DC systems require large andexpensive protection equipment, such as DC-rated circuit breakers. Thoseworking on DC systems must also wear substantial personal safetyequipment for protection.

Accordingly, for at least these reasons, there is on-going need in theart for a more cost-effective, efficient, and reliable solar powergeneration system.

BRIEF DESCRIPTION OF THE DRAWINGS

Reference will now be made to the drawings, which are not necessarilydrawn to scale, and wherein:

FIGS. 1A-1D show schematic representations of various existing solarpower generation systems;

FIG. 2 shows a schematic diagram of a solar power generation systemhaving distributed power converter nodes according to one embodiment;

FIG. 3A shows a deadband DC waveform generated by a power converter nodefrom the DC power received from a solar module according to oneembodiment;

FIG. 3B shows a deadband DC waveform generated by a power converter nodefrom the DC power received from a solar module according to anotherembodiment;

FIG. 4 shows a power converter node according to one embodiment;

FIG. 5 shows a circuit diagram of deadband converter circuit providedwithin a power converter node according to one embodiment;

FIG. 6 shows a grid sine wave and a corresponding node synchronizationsignal generated by a grid interface box according to one embodiment;

FIG. 7 shows a power-with-Ethernet cable according to one embodiment;

FIGS. 8A and 8B show cross-sectional and isometric cut-away views of thepower-with-Ethernet cable of FIG. 7 according to one embodiment;

FIGS. 9A and 9B show female and male power-with-Ethernet cableconnectors, respectively, according to one embodiment;

FIG. 10 shows a schematic diagram of a grid interface box (GIB)according to one embodiment;

FIGS. 11A and 11B show isometric views of a grid interface box chassisaccording to one embodiment;

FIG. 12 illustrates a power module according to one embodiment;

FIG. 13 illustrates a VAR modules according to one embodiment;

FIG. 14 illustrates an aggregator module according to one embodiment;

FIG. 15 shows a schematic diagram of a grid interface box having a3-phase WYE configuration according to one embodiment;

FIG. 16 shows a schematic diagram of a grid interface box having a3-phase delta configuration according to one embodiment; and

FIG. 17 shows a schematic diagram of a grid interface box having asingle phase configuration according to one embodiment.

DETAILED DESCRIPTION OF VARIOUS EMBODIMENTS

Various embodiments of the present invention now will be described morefully hereinafter with reference to the accompanying drawings, in whichsome, but not all embodiments of the inventions are shown. Indeed, theseinventions may be embodied in many different forms and should not beconstrued as limited to the embodiments set forth herein; rather, theseembodiments are provided so that this disclosure will satisfy applicablelegal requirements. The term “or” is used herein in both the alternativeand conjunctive sense, unless otherwise indicated. Like numbers refer tolike elements throughout.

Various embodiments of the present invention are directed to a solarpower generation system configured to more efficiently andcost-effectively generate power. According to various embodiments, thesolar power generation system includes a plurality of distributed powerconverter nodes each configured to convert DC power received from asolar module into a deadband DC waveform. The deadband DC powergenerated by each node is then transmitted to a centralized gridinterface box (GIB) configured to unfold the deadband DC waveform intoan AC signal suitable for transmission to an electric power grid.

As explained in greater detail herein, the use of distributed powerconverter nodes configured for producing a deadband DC waveform improvesthe efficiency and cost-effectiveness of the solar power generationsystem. For example, as the power converter nodes do not require all ofthe electronics necessary to convert DC power received from a solarmodule in to a full AC power signal, the power converter nodes aresmaller and lower-cost than existing micro-inverters. In addition,because the power converter nodes use fewer switching devices thatconventional micro-inverters, they will incur less switching losses andprovide improved efficiency. Furthermore, because the power convertersare configured to convert DC power into a deadband DC waveform—whichincludes regular periods of zero-voltage dead time—the transmission ofpower from the power converters to the GIB presents a reduced risk ofarcing, thereby improving the safety of the system as a whole.

In various embodiments, the distributed power converter nodes areconnected to one another—and ultimately to the GIB—bypower-with-Ethernet (PWE) cables and connectors. The power-with-Ethernetcables are each comprised, for example, of two power conductor cables,two twisted pairs of data communication cables, and two additionaluntwisted data communication cables. As explained in greater detailherein, the inclusion of separate power and data communication cableswithin the PWE cable enables efficient transmission of power alongsideuninterrupted data communication. As an example, the use of PWE cablesin the solar generation system enables quick and efficient powerconverter node synchronization. Most distributed architectures useeither wireless RF communication or Power Line Carrier Communication(PLCC). However, because the PWE cable provides a dedicated hardwiredcommunication line between the power converter nodes and the GIB,synchronization between the power converter nodes can be performed morequickly and at a lower cost. More broadly, the use of permanentcommunication wires enables the power converter nodes and GIB tocommunicate using higher bandwidth protocols, such as Ethernet. As aresult, larger amounts of data can be exchanged as compared with lowerbandwidth protocols, such as PLCC. Moreover, well-defined protocolsdeveloped for the internet can be used to ensure network security acrossthe solar power generation system.

Additionally, various embodiments of the GIB provided in the solar powergeneration system are provided with a modular configuration that enablesthe GIB to be easily scaled for different applications. As explained ingreater detail herein, the GIB is provided with removable power and VARmodules, which can be added and removed into the GIB's chassis as neededin order to provide the necessary capacity for converting deadband DCpower routed to the GIB into AC power suitable for supply to the grid.For this reason, each individual GIB unit can be used in a variety ofsolar power generation systems, including both small-scale (e.g.,residential) and large-scale (e.g., solar farm) systems.

FIG. 2 shows a schematic diagram of a solar power generation systemaccording to one embodiment of the present invention. In the illustratedembodiment of FIG. 2, the solar power generation system is generallycomprised of a plurality of solar modules 5, a plurality of powerconverter nodes 100, and grid interface box (GIB) 300. As explained indetail herein, the solar modules 5 are generally configured to convertsolar energy into DC power. The power converter nodes 100 are generallyconfigured to convert DC power received from the solar modules 5 into adeadband DC waveform, which is transmitted to the GIB 300. The GIB 300is configured to unfold the deadband DC waveform transmitted by thepower converter nodes 100 and output AC power suitable for supply to anelectric power grid. Each of these components of the solar powergeneration system will now be described in greater detail.

According to various embodiments, the solar modules 5 each comprise aplurality of solar panels configured to convert solar energy into DCpower output. In one embodiment, the solar modules 5 are each configuredto output approximately 300 watts of power at 30 volts. However, as willbe appreciated from the description herein, solar modules configured tooutput a variety of wattages can be implemented in the presentinvention. As shown in FIG. 2, each solar module 5 is connected to apower converter node 100 by power cables 7. In one embodiment, the powercables 7 may comprise PV rated cables having MC4 connectors. However, aswill be appreciated form the description herein, any electrical cableand connector suitable for transmitting DC power from a solar module 5to a power converter node 100 may be used.

According to various embodiments, the solar modules 5 depicted in FIG. 2may represent a plurality of modules installed in any solar powerproduction environment. As just some examples, the solar modules 5 mayrepresent a plurality of modules mounted on a residential home, aplurality of modules installed for powering a commercial or industrialbuilding, or a plurality of modules forming a large scale solar powerstation. As discussed in greater detail herein, each solar module 5 maybe connected to an individual power converter node 100 or, in variousother embodiments, multiple solar modules 5 may be connected (e.g., inseries) to an individual power converter node 100.

According to various embodiments, the solar power generation system'spower converter nodes 100 are each generally configured to receive DCpower generated by one or more solar modules 5 and convert the receivedDC power into a deadband DC waveform. As an example, FIG. 3A illustratesa deadband DC waveform 402 generated by a power converter node 100 fromthe DC power received from a solar module 5 according to one embodiment.As shown in FIG. 3A, the deadband DC waveform 402 is a rectifiedsinewave having periods of dead time 404—e.g., zero voltage—between thepeaks of the rectified sinewave. Unlike an AC waveform, the deadband DCwaveform 402 does not cross zero voltage. However, because the waveform402 includes regular deadbands 404 of zero voltage, an arc developing inthe solar generation system will extinguish during the deadband period404. As a second example, FIG. 3B illustrates a deadband DC waveform 406generated by a power converter node 100 from the DC power received froma solar module 5 according to another embodiment. As shown in FIG. 3B,the deadband DC waveform 406 is a modified trapezoidal waveform and—likethe waveform 402—includes deadband periods 408 between its peaks.

FIG. 4 illustrates a power converter node 100 according to oneembodiment. As shown in FIG. 4, the power converter node 100 includes ahousing 102, within which the power converter's electronic components(discussed in more detail herein) are positioned. In the illustratedembodiment, the housing 102 includes a body portion formed with aplurality of heat dissipating fins (e.g., formed from extrudedaluminum). According to various embodiments, the housing 102 may beconstructed from a thermally conductive material (e.g., metals, metalalloys, thermally conductive plastic, a combination of plastics andmetals and/or the like). In addition, a mounting bracket 104 is securedto the housing 102. According to various embodiments, the mountingbracket 104 is configured to enable the power converter 100 to bemounted directly to a respective solar module 5 or other surfaceproximate to the solar modules 5.

As shown in FIG. 4, a plurality of electrical connectors are provided onopposite ends of the power converter node's housing 102. At its firstend, the power converter node 100 includes a female electrical connector112 and a male electrical connector 114. According to variousembodiments, the electrical connectors 112, 114 are input powerconnectors configured to be secured to power cables 7 in order tofacilitate transmission of DC power generated by a solar module 5 to thepower converter node 100. As just one example, in the illustratedembodiment shown in FIG. 3, the electrical connectors 112, 114 are MC4connectors. As shown in FIG. 4, a second end of the power converter node100 includes a second pair of male and female electrical connectors 114,112 (e.g., that connect to a second solar power module).

The power converter node 100 also includes at its first end a pair offemale power-with-Ethernet (PWE) connectors 120. According to variousembodiments, the female PWE connectors 120 are configured to be securedto a power-with-Ethernet cable 200 in order to provide an electrical anddata communication connection between the power converter nodes 100 andthe GIB 300. In addition, the second end of the power converter node 100further includes a pair of male power-with-Ethernet (PWE) connectors130. Like the female PWE connectors 120, the male PWE connectors 130 areconfigured to be secured to a power-with-Ethernet cable 200 in order toprovide an electrical and data communication connection between thepower converter nodes 100 and the GIB 300. Various features of the PWEconnectors 120, 130 are described in greater detail herein with respectto FIGS. 6-8.

FIG. 5 shows a circuit diagram of deadband converter circuit 160provided within the power converter node 100 according to oneembodiment. According to various embodiments, the deadband powerconverter circuit 160 is a DC-DC converter disposed within the powerconverter node's housing 102. On the left side of the FIG. 5's circuitdiagram, the circuit 160 includes a pair of voltage inputs 162 (positiveand negative). In the illustrated embodiment, the voltage inputs 162 areelectrically connected to one of power converter node's pairs ofelectrical connectors 112, 114.

Power received through the voltage inputs 162 is routed to a pair ofswitching transistors 172, 173, which are configured to regulate powerflow through the circuit 160. By varying the switching times of thetransistors 172, 173, the circuit 160 is able to transform the flat DCwaveform received from a solar module 5 into a shaped DC waveform havingdeadbands (e.g., as shown in FIGS. 3A and 3B). The deadband DC waveformis then output from the circuit via a pair of voltage outputs 164(positive and negative). In the illustrated embodiment, the voltageoutputs 164 are electrically connected to power connector contacts inone of the power converter node's PWE connectors 120, 130. Inparticular, as discussed in more detail herein, the embodiment shown inFIG. 4 includes two independent node circuits (e.g., of the type shownin FIG. 5) within the housing 102. Each circuit uses a set of inputsfrom the solar module 112, 114, input from a PWE connector 120, and anoutput from a PWE connector 130. The two circuits are completelyindependent and can be connected to each other externally in eitherseries or parallel by means of the external PWE cable 200. To connectthe circuits in series, a single loopback jumper can be used (e.g., asshown on the second node 100 from the left in FIG. 2). To connect thetwo circuits in parallel, two sets of jumpers can be used on both setsof connectors (120, 130) (e.g., as shown on the second node from theright in FIG. 2).

In the illustrated embodiment of FIGS. 2-5, the power converter nodes100 are each rated, for example, to handle 300 W of power from each ofthe solar modules 5. However, in various other embodiments, the powerconverter nodes 100 can be configured to handle additional power (e.g.,400-800 W). In one embodiment, the deadband DC waveform generated by thepower converter nodes 100 is configured to have deadbands 404 eachhaving a pulse width of approximately 100 microseconds and occurringevery 8.33 milliseconds (e.g., in a 60 hz signal).

Additionally, according to certain embodiments, the frequency and widthsof the deadbands 404 can be adjusted by the transistors 172, 173. Forexample, in certain embodiments, the deadbands 404 can be adjusted fortime length such that power transmission is optimized and, as linevoltage increases, the deadband width may be increased.

According to various embodiments, the deadband converter circuit 160 isalso configured to synchronize its deadband DC waveform to the electricgrid. As explained in greater detail below, the solar power generationsystem's GIB 300 is configured to monitor the sinusoidal voltage on theelectric grid and identify zero crossings in the voltage (e.g., detectedby a change in polarity of the monitored voltage). When a zero crossingof the grid sine wave is detected, the GIB generates a transition ineither voltage or current in a synchronization wire provided in the PWEcable 200. For example, the GIB could transition from low voltage tohigh voltage or high voltage to low voltage. If a current signal isutilized instead of a voltage signal, then a transition from highcurrent to low current or vice versa is utilized. As an example, FIG. 6illustrates an example of a grid sine wave 191 and a corresponding nodesynchronization signal 191 generated by the GIB 300.

According to various embodiments, each power converter node 100 in thesystem monitors a signal line in the PWE cable 200 for transitions. Whena transition in either voltage or current is detected on thesynchronization wire, a node 100 starts generating a rectified deadbandwaveform to feed to the GIB 300. In this way, all of the distributedpower converter nodes 100 can be synchronized to the electric grid.

In the power converter node 100 embodiment shown and described withrespect to FIGS. 4 and 5, the power converter node 100 includes a pairof deadband converter circuits 160. Referring for example to FIG. 4, thevoltage inputs 162 of a first circuit 160 are electrically connected toa first pair of the node's electrical connectors 112, 114, while thevoltage inputs 162 of a second circuit 160 are connected to the other ofthe node's electrical connectors 112, 114. Likewise, the voltage outputs164 of the first circuit 160 are electrically connected to one of thenode's PWE connectors 120, 130, while the voltage outputs 164 of asecond circuit 160 are connected to the other of the PWE connectors 120,130. As a result, the illustrated embodiment of the power converter node100 is provided with a dual-node architecture. In this embodiment, thedual deadband converter circuits 160 can be arranged in parallel orseries via PWE cables 200 connecting the power converter nodes 100 toone another. This is shown, for example, in FIG. 2, which—from left toright—illustrates the first three power converter nodes 100 connected inseries by PWE cables 200, while the next three power converter nodes 100are connected in parallel. In certain embodiments, the PWE connectors130 can be configured as inputs from other power converter nodes 100,while the PWE connectors 120 can be configured as outputs.

As noted earlier with respect to FIG. 2, the power converter nodes 100are connected to one another—and to the GIB 300—by PWE cables 200. FIG.7 shows a PWE cable 200 according to one embodiment. As shown in FIG. 7,each PWE cable 200 includes a female PWE connector 120 at one end and amale PWE connector 130 at the opposite end.

According to various embodiments, each PWE cable 200 is comprised of twopower conductors, two twisted pairs of conductors for datacommunication, and two additional untwisted data communicationconductors. FIGS. 8A and 8B illustrate cross-sectional and isometriccut-away views of the PWE cable 200, respectively, according to oneembodiment. As shown in FIG. 8A, the PWE cable 200 includes two powerconductors 202 positioned adjacent to one another, two twisted pairs ofconductors for data communication 204 positioned on opposite sides ofthe power conductors 202, and two additional untwisted datacommunication conductors 208. In the illustrated embodiment, the powerconductors 202 are AWG 12 7 strand copper wires coated with a protectivematerial (e.g., PVC or HDPE insulation). Additionally, in theillustrated embodiment, the twisted pair data communication conductors204 and untwisted data communication conductors 208 are AWG 24 solidcopper wires coated with a protective material (e.g., PVC or HDPEinsulation). As shown in FIGS. 8A and 8B, the power conductors 202,twisted pairs of data communication conductors 204, and untwisted datacommunication conductors 208 wrapped with a protective wrap 212 (e.g., athin polyester wrap) and positioned within a cable jacket 210 (e.g.,PVC, PE, or TPE cable jacket). In the illustrated embodiment of FIGS. 8Aand 8B, the combination of cables 202, 204, and 208 enables a roundcable (e.g., as can be seen from the cross-sectional view of FIG. 8A).

According to various embodiments, the PWE cable's power conductors 202are configured to transmit the deadband DC power generated by therespective power converter nodes 100 throughout the solar powergeneration system. Separately, the twisted pairs of data communicationconductors 204 and untwisted data communication conductors 208 areconfigured to enable data communication the between the power converternodes 100 and the GIB 300. For example, in one embodiment, the nodesynchronization signal 193 (shown in FIG. 6) generated by the GIB 300can be transmitted to the various power converter nodes 100 via theuntwisted data communication conductors 208 (or, alternatively, via thetwisted pairs of data communication conductors 204). Additional datacommunication, such as for the purpose of monitoring the performance ofthe power converter nodes 100 and their respective solar modules 5, canbe transmitted along the remaining untwisted data communicationconductors 204, 208. In various embodiments, by providing separate,isolated conductors for power and data communication, the powergenerated by the power converter nodes 100 can be distributeduninterrupted along the PWE cables 200 to the GIB 300.

The PWE cable's female and male PWE connectors 120, 130 are shown inFIGS. 9A and 9B according to one embodiment. As shown in FIG. 9A, thefemale PWE connector 120 includes a pair of power connector protrusions121, which extend outwardly from the connector and are laterally spacedfrom one another. According to various embodiments, the power connectorprotrusions 121 include electrical contacts disposed in a recessedfashion within the protrusions and that are electrically connected tothe PWE cable's power cables 202.

The female PWE connector 120 also includes an upper data connectorprotrusion 123 and a lower data connector protrusion 126. Both the upperand lower data connector protrusions extend outwardly from the connector120 and disposed at least partially between the power connectorprotrusions 121. As shown in FIG. 9A, the upper data connectorprotrusion 123 includes three electrical contacts disposed in a recessedfashion within the upper data connector protrusion 123. According tovarious embodiments, two of the upper data connector's electricalcontacts are electrically connected to one of the PWE cable's twistedpairs of data communication conductors 204, while the third of the upperdata connector's electrical contacts are electrically connected to oneof the PWE's cables untwisted data communication conductors 208. Inparticular, in the illustrated embodiment, the upper data connectorprotrusion's three electrical contacts are arranged in a triangle, withtwo of the electrical contacts disposed laterally adjacent to oneanother and the third electrical contact disposed below and between thefirst two electrical contacts. Specifically, in the illustratedembodiment, the lower electrical contact is positioned partially betweenthe power connector protrusions 121.

Likewise, the lower data connector protrusion 126 includes threeelectrical contacts disposed in a recessed fashion within the lower dataconnector protrusion 126. According to various embodiments, two of thelower data connector's electrical contacts are electrically connected toone of the PWE cable's twisted pairs of data communication conductors204, while the third of the upper data connector's electrical contactsare electrically connected to one of the PWE's cables untwisted datacommunication conductors 208. In particular, in the illustratedembodiment, the lower data connector protrusion's three electricalcontacts are arranged in a triangle, with two of the electrical contactsdisposed laterally adjacent to one another and the third electricalcontact disposed above and between the first two electrical contacts.Specifically, in the illustrated embodiment, the upper electricalcontact is positioned partially between the power connector protrusions121.

The female PWE connector 120 also includes a pair of laterally disposedfastener tabs 129. As shown in FIG. 9A, the fastener tabs 129 aregenerally thin, resilient tabs extending outwardly from lateral sides ofthe connector, adjacent outer portions of the power connectorprotrusions 121. As discussed in greater detail below, the fastener tabs129 are configured to engage the male PWE connector 130 and enable theconnectors 120, 130 to be selectively and removably secured to oneanother.

As shown in FIG. 9B, the male PWE connector 130 includes a pair of powerconnector cavities 131, which extend inwardly into the connector and arelaterally spaced from one another. According to various embodiments, thepower connector cavities 131 include protruding electrical contactsdisposed centrally within the cavities and that are electricallyconnected to the PWE cable's power conductors 202. In particular, thepower connector cavities 131 are dimensioned to receive the powerconnector protrusions 121 of the female PWE connector 120 such that themale connectors' power connector electrical contacts are inserted withinthe female connector's power connector contacts, thereby electricallyconnecting the power portions of the contacts 120, 130.

The male PWE connector 130 also includes an upper data connector cavity133 and a lower data connector cavity 136. As shown in FIG. 9B, theupper data connector cavity 133 includes three protruding electricalcontacts disposed within the upper data connector cavity 133 andarranged in triangular pattern. According to various embodiments, two ofthe upper data connector cavity's protruding electrical contacts areelectrically connected to one of the PWE cable's twisted pairs of datacommunication conductors 204, while the third of the upper dataconnector cavity's electrical contacts are electrically connected to oneof the PWE's cables untwisted data communication conductors 208. Inparticular, the upper data connector cavity 133 is dimensioned toreceive the upper data connector protrusion 123 of the female PWEconnector 120 such that the male connector's data connector electricalcontacts are inserted within the female connector's data connectorelectrical contacts, thereby connecting the data portions of thecontacts 120, 130.

Likewise, the lower data connector cavity 136 includes three protrudingelectrical contacts disposed within the lower data connector cavity 136and arranged in triangular pattern. According to various embodiments,two of the lower data connector cavity's protruding electrical contactsare electrically connected to one of the PWE cable's twisted pairs ofdata communication conductors 204, while the third of the upper dataconnector cavity's electrical contacts is electrically connected to oneof the PWE's cables untwisted data communication conductors 208. Inparticular, the lower data connector cavity 136 is dimensioned toreceive the lower data connector protrusion 126 of the female PWEconnector 120 such that the male connector's data connector electricalcontacts are inserted within the female connector's data connectorelectrical contacts, thereby connecting the data portions of thecontacts 120, 130.

The male PWE connector 130 also includes a pair of laterally disposedfastener cavities 139. As shown in FIG. 9B, the fastener cavities 139are positioned adjacent outer portions of the power connector cavities131. In various embodiments, the fastener cavities 139 are dimensionedto engage the resilient fastener tabs 129 of the female PWE connector120 when the fastener tabs 129 are inserted within the fastener cavities139. In this way, the connectors 120, 130 to be selectively andremovably secured to one another.

According to various embodiments, based on the design and configurationof the power converter nodes 100, the PWE cable 200 may be providedwithout the twisted pairs of data communication conductors 204 (e.g., insimple embodiments where the data communication provided by the cablesis not necessary).

According to various embodiments, the grid interface box (GIB) 300 isconfigured to unfold the deadband DC power generated by the powerconverter nodes 100 into an AC signal suitable for transmission to anelectric power grid. In addition, the GIB 300 serves as a communicationsgateway, enabling data transmission between the power converter nodes100 and remote systems outside of the solar power generation system(e.g., remote computers or other devices). As discussed in detail below,the GIB 300 is also provided with a modular configuration that allows itto be easily scaled up (or down) to accommodate various solar powergeneration environments, including residential, commercial, and utilityscale applications.

FIG. 10 shows a schematic diagram of the grid interface box (GIB) 300according to one embodiment. As shown in FIG. 10, the GIB 300 iscomprised of a chassis 302, which is configured for housing a pluralityof removable power modules 320, VAR modules 330, and at least oneaggregator module 340. FIGS. 11A and 11B show the GIB chassis 302 inisolation according to one embodiment. As shown in FIG. 11A, the GIBchassis 302 includes a door 312, which can be open and closed to accessthe interior portion of the chassis 302. In addition, FIG. 11Billustrates schematically a plurality of slots 314 provided in theinterior portion of the chassis 302. According to various embodiments,the slots 314 can be dimensioned to receive and secure the removablemodules 320, 330, 340 described herein.

Referring back to FIG. 10, the GIB's chassis 302 further includes aninternal bus bar assembly 310, to which the modules 320, 330, 340 can beelectrically connected when inserted into the chassis' slots 314. As anexample, in one embodiment, the bus bar assembly is comprised of a twomolding claim-shell with two, three, or four stamped copper bus barswith 18 mm modularity and a plurality of stabs configured for engagingthe modules 320, 330, 340. The chassis also includes a line connection304 for connecting the GIB 300 to an electric grid. The line connectionwiring may enter, for example, through the bottom of the chassis 302through standard cable glands and knockouts. The GIB 300 also includes aplurality of string connectors 306, which facilitate connection of thepower modules 320 within the GIB to strings of power converters 100 (asshown, for example, in FIG. 2). As one example, the string connectors306 may enter the GIB chassis 302 through dedicated cable glands withsplit rubber grommets. The line connection 304 is also routed through anisolator 308, which is configured as a disconnect switch. The GIB alsoincludes a surge arrestor block 309 (e.g., for plug in Varistor andDischarge Tube Modules).

According to various embodiments, the GIB 300 is also configured withanti-islanding functionality to disable the GIB when it detects that theelectric grid has entered an islanded condition.

According to various embodiments, the GIB's power modules 320 aregenerally configured to unfold the deadband DC power transmitted by thepower converter nodes 100 to the GIB 300 in order to convert that signalinto AC power. The resulting AC power is then delivered to an electricgrid via the line connection 304. In the illustrated embodiment of FIG.2, for example, the power modules 320 are configured to convert to AC ina 3-phase power system. However, in various other embodiments, the powermodules 320 may be configured to convert to AC in a single-phase orsplit-phase power system. In particular, the power modules may beconfigured to function for both 120V and 240V systems.

FIG. 12 illustrates a single power module 320 according to oneembodiment. As shown in FIG. 12, power module 320 includes a pair of PWEconnectors 120 at its upper end, which facilitate connection to thestring connectors 306 feeding power from a string of power converternodes 100. In addition, the power module 320 includes a plurality ofelectrical contacts 322 at its opposite end, which are configured tointerface with the tabs of the GIB's bus bar assembly 310. In otherwords, when the power module 320 is inserted into one of the GIB's slots314, the bus bar assembly's tabs will be inserted into the electricalcontacts 322 of the power module 320, thereby electrically connectingthe power module 320 with the remaining GIB components.

As discussed earlier herein in relation to FIG. 3A, in one embodimentthe power converter nodes 100 are configured to generated a deadband DCwaveform 402 shaped as a rectified sinewave. As a result, the GIB'spower modules 320 are configured to invert the waveform 402 by invertingevery other pulse in the waveform 402, which are easily identifiablefrom the deadband periods 404. Additionally, as discussed earlierherein, the GIB is configured to monitor the grid voltage (e.g., via theline connection 304) in order to generate a synchronization signaltransmitted to the power converter nodes 100 (e.g., via the stringconnectors 306 and PWE cables 200). As a result, the deadband DCwaveform received and inverted by the GIB is already synchronized to theelectric grid. Moreover, because the GIB 300 is powered by the grid, ifa particular power converter node 100 loses power, the GIB'ssynchronization signal will still be transmitted to the remainingoperational nodes 100, thereby ensuring synchronized AC output in phasewith the utility grid AC phase.

According to various embodiments, the power module 320 may be configuredto process various amounts of power. In the illustrated embodiment ofFIGS. 2 and 10, for example, the power modules 320 are each 40 A powermodules rated at 10 kW. Furthermore, in the illustrate embodiment ofFIGS. 2 and 10, six power modules 320 are provided in the slots 314 ofthe GIB 300 and are secured to the bus bar assembly 310. As a result,the GIB 300 is shown in a configuration scaled to handle 60 kW of power.

According to various embodiments, the GIB's VAR modules 330 aregenerally configured to adjust the amount of reactive power that issupplied to the grid. Many utilities demand that power that is injectedinto the grid be power factor adjustable. To adjust the power factor ofinjected power, the inverter can exert control over its “real” or“active” power (measured in kW) and its reactive power (measured in VoltAmps Reactive or VARs). The GIB provides the desired about of “real”power to the grid while the VAR module 330 supplies reactive power tothe grid. In order to adjust the power factor to the desired level, aVAR module 330 is generally provided for each power module 320 insertedinto the GIB 330.

FIG. 13 illustrates a VAR module 330 according to one embodiment. Asshown in FIG. 13, the VAR module 330 includes a plurality of electricalcontacts 332, which are configured to interface with the tabs of theGIB's bus bar assembly 310. In other words, when the VAR module 330 isinserted into one of the GIB's slots 314, the bus bar assembly's tabswill be inserted into the electrical contacts 332 of the VAR module 330,thereby electrically connecting the VAR module 330 with the remainingGIB components. In the embodiment shown in FIG. 13, the VAR module is acombined 3-phase module, essentially consisting of three 30 A VARmodules joined together. As a result, each VAR module 330 of the typeshown in FIG. 13 is configured to perform power factor correction forthree power modules 320 in the GIB 300.

As will be appreciated from the description herein, the GIB 300 can bescaled to handle various thresholds of power by adding or removing powermodules 320 and VAR modules 330. For example, as noted above, the GIB300 shown in FIGS. 2 and 10 includes six power and VAR modules 320, 330and is therefore rated at 60 kW. However, by including only three powermodules 320 and VAR modules 330, for example, the GIB 300 rating couldbe scaled back to 30 kW. The opposite would be true by adding additionalpower and VAR modules 320, 330. As a result, the modular configurationof the GIB 300—which enables the power and VAR modules 320, 330 to beeasily added or removed from the GIB chassis—allows for the GIB to beeasily scaled up (or down) to accommodate various solar power generationenvironments, including residential (e.g., 10 kW), commercial (e.g.,30-60 kW), and utility scale (e.g., 120 kW+) applications.

According to various embodiments, the GIB's aggregator module 340 isconfigured to control the operation of the GIB 300 and function as acommunications gateway between the remaining components of the solarpower generation system (e.g., power converter nodes 100) and remotedevices (e.g., computers configured for interoperability with the GIB300). In the illustrated embodiment of the FIGS. 2 and 10, theaggregator module 340 includes at least one dedicated processor andassociated memory storage for running software and applications relatedto the GIB's functionality. In particular, the aggregator module 340 isconfigured to send and receive data from the power converter nodes 100and power modules 320 via the bus bar assembly 310 and the various PWEcables 200 connecting the nodes 100 to the GIB 300. In addition, theaggregator module 340 includes a Wi-Fi antenna 346, which is configuredto provide communication with the aggregator module 340 over a wirelessinternet network, and an Ethernet uplink 344, which is configured toprovide communication with the aggregator module 340 over a dedicatednetwork.

FIG. 14 illustrates an aggregator module 340 according to oneembodiment. As shown in FIG. 14, the aggregator module 340 includes aplurality of electrical contacts 342, which are configured to interfacewith the tabs of the GIB's bus bar assembly 310. In other words, whenthe aggregator module 340 is inserted into the GIB, the bus barassembly's tabs will be inserted into the electrical contacts 342 of theaggregator module 340, thereby electrically connecting the aggregatormodule 340 with the remaining GIB components.

In various embodiments, the aggregator module 340 is configured tofunction as a bridge for internal and external network connectivity,handle supervisory control and data acquisition operations from thegrid, and collect and perform edge mining on all sensor data (e.g.,collected from the power converter nodes 100), and to host installer andmaintainer applications. The aggregator also provides system widecontrol functions to shut down or scale back output when externalcommands (e.g., from the utility) are received.

As discussed earlier herein, the GIB 300 can be configured to convert toAC in a 3-phase power system or single (or split-phase) power system at120V or 240V. As examples, FIG. 15 shows the GIB 300 in a 3-phase WYEconfiguration, FIG. 16 shows the GIB 300 in a 3-phase deltaconfiguration, and FIG. 17 shows the GIB 300 in a single-phaseconfiguration.

While this specification contains many specific embodiment details,these should not be construed as limitations on the scope of anyinventions described herein, but rather as descriptions of featuresspecific to particular embodiments of particular inventions. Certainfeatures that are described herein in the context of separateembodiments can also be implemented in combination in a singleembodiment. Conversely, various features that are described in thecontext of a single embodiment can also be implemented in multipleembodiments separately or in any suitable sub-combination. Moreover,although features may be described above as acting in certaincombinations, one or more features from a combination can in some casesbe excised from the combination, and the combination may be directed toa sub-combination or variation of a sub-combination.

Moreover, many modifications and other embodiments of the inventions setforth herein will come to mind to one skilled in the art to which theseinventions pertain having the benefit of the teachings presented in theforegoing descriptions and the associated drawings. Therefore, it is tobe understood that the inventions are not to be limited to the specificembodiments disclosed and that modifications and other embodiments areintended to be included within the scope of the application.

That which is claimed:
 1. A solar power generation system comprising: aplurality of solar modules each configured for generating a DC powersignal; a plurality of power converter nodes each configured forreceiving a DC power signal from at least one of the plurality of solarmodules and converting the DC power signal into a converted power signalcomprising deadband DC waveform, wherein the deadband DC waveformincludes periods of zero voltage between the waveform's peaks; and agrid interface box configured for receiving the converted power signalsfrom the plurality of power converter nodes, unfolding the convertedpower signals, and outputting AC power to an electric grid; wherein eachpower converter node is connected to at least one other power converternode by one or more power-with-ethernet cables; and wherein the one ormore power-with-ethernet cables each comprise a jacket, one or morepower conductors positioned within the jacket, and one or more datacommunication conductors positioned within the jacket.
 2. The solarpower generation system of claim 1, wherein the deadband DC waveformcomprises a rectified sinewave.
 3. The solar power generation system ofclaim 1, wherein each of the plurality of power converter nodes includesa deadband converter circuit configured for generating the convertedpower signal, the deadband converter circuit in communication with apositive voltage input, negative voltage input, positive voltage output,and negative voltage output.
 4. The solar power generation system ofclaim 1, wherein each of the plurality of power converter nodescomprises a first positive voltage input, a first negative voltageinput, a first positive voltage output, a first negative voltage output;a second positive voltage input, a second negative voltage input, asecond positive voltage output, and a second negative voltage output. 5.The solar power generation system of claim 4, wherein the first deadbandconverter circuit and the second deadband converter circuit areconfigured for being selectively connected in series or parallel via thefirst and second positive voltage inputs, first and second negativevoltage inputs, first and second positive voltage outputs, and first andsecond negative voltage outputs.
 6. The solar power generation system ofclaim 1, wherein each of the power converter nodes is configured toadjust the frequency and width of the periods of zero voltage in thedeadband DC waveform.
 7. The solar power generation system of claim 1,wherein the periods of zero voltage in the deadband DC waveform have apulse width of approximately 100 microseconds and occur approximatelyevery 8.33 milliseconds.
 8. The solar power generation system of claim1, wherein the grid interface box is configured to monitor thesinusoidal voltage on the electric grid, generate a node synchronizationsignal, and transmit the node synchronization signal to the plurality ofpower converter nodes; and wherein the plurality of power converternodes are configured to receive the node synchronization signal andgenerate converted power signals synchronized to the electric grid. 9.The solar power generation system of claim 1, wherein the grid interfacebox comprises one or more power modules configured for unfolding theconverted power signals received from the plurality of power convertersand outputting AC power via a line connection.
 10. The solar powergeneration system of claim 9, wherein the grid interface box furthercomprises one or more VAR modules configured to adjust the amount ofreactive power to the grid via the line connection.
 11. The solar powergeneration system of claim 10, wherein the one or more power modules andone or more VAR modules are configured for being selectively engagedwith an internal bus bar provided in the grid interface box and areremovable from the grid interface box.
 12. The solar power generationsystem of claim 1, wherein the one or more data communication conductorsare packaged together within a protective wrap.
 13. A power converternode configured for converting DC power into a modified DC waveform, thepower converter node comprising: a housing; one or more input powerconnectors provided on the housing and configured for receiving a DCpower signal; a converter circuit positioned within the housing andconfigured for converting the DC power signal into a converted powersignal comprising a converted waveform having reoccurring portions ofzero voltage between the waveform's peaks; and one or more output powerconnectors provided on the housing and configured for outputting theconverted power signal generated by the converter circuit, wherein theone or more output power connectors are configured for interfacing withat least one power-with-ethernet cable, wherein the at least onepower-with-ethernet cable comprises a jacket, one or more powerconductors positioned within the jacket, and one or more datacommunication conductors positioned within the jacket.
 14. The powerconverter node of claim 13, wherein the converted DC waveform comprisesa rectified sinewave having periods of zero voltage between thewaveform's peaks.
 15. The power converter node of claim 14, theconverter circuit is configured to adjust the frequency and width of theperiods of zero voltage in the converted DC waveform.